1. Field of Invention
This invention pertains to the art of methods and apparatuses for occupant restraint assemblies, and more specifically to methods and apparatuses for a vehicle occupant sensing apparatus.
2. Description of the Related Art
It is well known to provide occupant restraint assemblies for vehicles, such as passenger cars, to restrain an occupant during a crash. Typically, an occupant restraint assembly includes an airbag and an inflator for inflating the airbag. When a crash is sensed by some type of crash sensor, typically mounted to the vehicle, the airbag is deployed, that is inflated with a gas. The inflated airbag then restrains the motion of the occupant during the crash. Preferably, the airbag may be deployed at varying deployment conditions depending on the occupant's size and location. A properly positioned adult, for example, may require that the airbag be deployed at full or "normal" strength. When no occupant is present, it is typically better to prevent the airbag from deploying at all.
A common problem known in the art relates to the use of an occupant restraint assembly with a child seat. Child seats are used to restrain smaller occupants, such as small children and infants. Child seats commonly come in two types, front facing and back facing. A front facing child seat is a child seat in which both the child seat and the occupant within the child seat face toward the front of the vehicle. Similarly, a back facing child seat is a child seat in which both the child seat and the occupant within the child seat face toward the back of the vehicle. It is currently an accepted standard in the art that in cases where a back facing child seat is present an associated airbag should not be deployed. In cases where a front facing child seat is present, on the other hand, it may be desirable to deploy the airbag either at full strength or at a reduced strength. What is needed then, is a reliable apparatus and method for sensing the presence of a child seat and whether it is front facing or back facing.
Another problem known in the art relates to the use of ultrasonic devices. Ultrasonic devices transmit and receive waves having a frequency above the human ear's audible limit in order to sense the distance between an object and the ultrasonic device. In the art of occupant restraint assemblies, it is know to use ultrasonic devices to sense the distance between the ultrasonic device and an object, such as an occupant, positioned on the seat of a vehicle. Such ultrasonic devices are known to emit a "clicking" sound that may be considered annoying by vehicle occupants. Therefore, a method and apparatus for reducing or eliminating such clicking sounds is desirable.
The present invention provides methods and apparatuses for determining the presence of an object, such as an occupant, in a vehicle. It also determines the presence of a child seat and whether the child seat is front facing or rear facing. In addition, the present invention provides methods and apparatuses for reducing the clicking sounds known with the use of ultrasonic devices. The difficulties inherent in the art, are therefore overcome in a way that is simple and efficient, while providing better and more advantageous results.